Monkey Study Suggests Long-Term Use of ADHD Drugs Safe

THURSDAY, July 19 (HealthDay News) -- Long-term use of drugs to treat attention-deficit hyperactivity disorder (ADHD) does not affect brain development or increase the risk of drug abuse, according to a study conducted in monkeys.

Monkeys are good for this type of research because they have relatively long periods of childhood and adolescence that feature hormonal and physical changes much like those that occur in humans, explained the researchers from Wake Forest Baptist Medical Center in Winston-Salem, N.C.

The ages of the 16 juvenile monkeys used in this study were equivalent to 6- to 10-year-old humans. Eight of the monkeys received an extended-release form of the ADHD drug Ritalin for more than a year, which is equivalent to about four years in human children. Eight other monkeys in a control group did not receive any drug treatment.

Imaging scans of all the monkeys' brains were conducted before and after the study, to detect any changes in brain chemistry and structure. The researchers also assessed the monkeys' physical growth.

"After one year of drug therapy, we found no long-lasting effects on the neurochemistry of the brain, no changes in the structure of the developing brain," Linda Porrino, chairwoman of Wake Forest's physiology and pharmacology department, said in a university news release. "There was also no increase in the susceptibility for drug abuse later in adolescence."

"We were very careful to give the drugs in the same doses that would be given to children," she added. "That's one of the great advantages of our study is that it's directly translatable to children."

The study was published online in the July issue of the journal Neuropsychopharmacology.

As many as 5 percent to 7 percent of elementary school children in the United States have been diagnosed with ADHD, which is a behavioral disorder that causes inattention, hyperactivity, impulsivity or a combination of these traits.

Many children with ADHD are prescribed drugs, but little is known about their long-term effects.

"Our study showed that long-term therapeutic use of drugs to treat ADHD does not cause long-term negative effects on the developing brain and, importantly, it doesn't put children at risk for substance abuse later in adolescence," Porrino said.

Although monkeys are similar to humans, the results of this research may not be the same in humans.

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